Changes for luaPoB to support pyPoB's build xmls

[pHiney]

Fixes Nothing. Accumulation PR of needed adjustments (hopefully, just this one)

Description of the problem being solved:

1. NotesHTML tag

pyPob or (PyPob) introduces a NotesHTML xml tag which would be lost if the build.xml was loaded into the lua version.

Steps taken to verify a working solution:

1. NotesHTML tag

• Save a build from pyPoB (https://pastebin.com/cjxaAMW)
• Load into luaPoB
• change something and save the build
• Open the.xml in a text editor and search for NotesHTML tag to see that it is preserved.

Link to a build that showcases this PR:

1. NotesHTML tag

https://pastebin.com/cjxaAMW

Before screenshot:

1. NotesHTML tag

N/A

After screenshot:

1. NotesHTML tag

N/A